1. Field of the Invention
The present invention relates to an ink jet recording ink which can yield a high-quality print having no significant feathering or bleeding on plain papers, recycled papers, or coated papers.
2. Background Art
Ink jet recording is a method wherein an ink is ejected as a droplet through fine nozzles to record letters or figures onto the surface of a recording medium. Ink jet recording systems which have been put to practical use include: a method wherein an electrical signal is converted to a mechanical signal using an electrostrictive strain to intermittently eject an ink reservoired in a nozzle head section, thereby recording letters or symbols on the surface of a recording medium and a method wherein an ink, reservoired in a nozzle head section, in its portion very close to the ejection portion is rapidly heated to create a bubble and the ink is intermittently ejected by volume expansion created by the bubble to record letters or symbols on the surface of a recording medium.
Properties required of inks used in the ink jet recording are such that the drying property of the print is good, no feathering is created, printing can be homogeneously performed on the surface of various recording medium, and, in the case of multi-color printing, color-to-color intermixing does not occur, and the printed image possesses excellent waterfastness and rubbing/scratch resistance.
In order to overcome these requirements, various ink compositions have been proposed in the art.
For example, Japanese Patent Publication 2907/1990 proposes utilization of glycol ether as a wetting agent, Japanese Patent Publication 15542/1989 proposes utilization of a water-soluble organic solvent, and Japanese Patent Publication 3837/1990 proposes utilization of a dye solubilizer.
Further, in order to improve the penetrability of the ink, U.S. Pat. No. 5,156,675 proposes addition of diethylene glycol monobutyl ether, U.S. Pat. No. 5,183,502 proposes addition of Surfynol 465, an acetylene glycol surfactant, and U.S. Pat. No. 5,196,056 discloses addition of both diethylene glycol monobutyl ether and Surfynol 465. In this connection, diethylene glycol mono-n-butyl ether is known also as butylcarbitol and described, for example, in U.S. Pat. No. 3,291,580. Further, utilization of an ether of diethylene glycol has been studied in U.S. Pat. No. 2,083,372. Furthermore, Japanese Patent Laid-Open No. 147861/1981 proposes use of a pigment and triethylene glycol monomethyl ether in combination.
In the ink composition using a pigment, an attempt to suppress penetration of the ink in the surface of a recording medium has been made to ensure the print quality.
In some cases, however, when the ink composition does not penetrate into the recording medium to a certain extent, the pigment is left on the surface of the recording medium, deteriorating the rubbing/scratch resistance of the print. Further, in recent years, a recording medium has been utilized wherein a surface gloss layer is provided, a gloss is put on the recorded image and added value is imparted to the image. A pigment-type ink capable of realizing an image having good rubbing/scratch resistance on the recording medium has been desired in the art.